Does anybody eat string algae?


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I've got a medium size pond, about 3500 gallons, just 4 10" koi, they do eat quite a lot already this spring, so I suppose a fair amount of phosphorous is introduced to the water... The pond does get almost full sun, some shade in morning and late afternoon. An old plastic bead filter and UV sterilizer keep the water quite clear. I try to exchange about 100 gallons a week with (nasty chloraminated) city water, but sometimes I miss a week. I scoop out gallons of string algae from this thing weekly, after quite a search, a narrow plastic shrub rake works well. Is there some relatively harmless animal inhabitant that would simply east this stuff?

KH
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brokensword

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I've got a medium size pond, about 3500 gallons, just 4 10" koi, they do eat quite a lot already this spring, so I suppose a fair amount of phosphorous is introduced to the water... The pond does get almost full sun, some shade in morning and late afternoon. An old plastic bead filter and UV sterilizer keep the water quite clear. I try to exchange about 100 gallons a week with (nasty chloraminated) city water, but sometimes I miss a week. I scoop out gallons of string algae from this thing weekly, after quite a search, a narrow plastic shrub rake works well. Is there some relatively harmless animal inhabitant that would simply east this stuff?

KH
San Jose, California
well, not sure if this is a solution to you, but I havent' had any string algae for years. Having upflow wetland filtration (bog) and lots of plants, I think has stopped all that nusiance. I also have never changed water, either. A UV will kill the existing free-floating algae which just dies and heads to the bottom of your pond to be used as more fertilizer. If you don't have a good quantity of plants acting in your pond, the algae has a chance to get a foothold. Out-compete algae and you can eliminate or at least minimize it's effect.

Some here have string algae in the spring but once their system gets up and running (bog and plants), it generally goes away.
 
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Thanks. I do have two medium size narrow leaf cattails (Typha angustifolia) in sturdy cloth bags (bag pots? pot bags?) in the pond, near the waterfall. They don't seem do do much about absorbing nutrients from the water. Adding a bog would involve redesigning the pond layout..... Perhaps I could put some shorter containers in and around the waterfall features and make a bog of sorts there....
 

brokensword

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Thanks. I do have two medium size narrow leaf cattails (Typha angustifolia) in sturdy cloth bags (bag pots? pot bags?) in the pond, near the waterfall. They don't seem do do much about absorbing nutrients from the water. Adding a bog would involve redesigning the pond layout..... Perhaps I could put some shorter containers in and around the waterfall features and make a bog of sorts there....
you could also get some floating plant nets and use water hyacinth and/or water lettuce; these two alone will really help keep the water column clean, though the real magic is in a bog like filter where you have a lot of surface area for the denitrifying bacteria to colonize. If your koi are better behaved, you might not need the net baskets. It's good to try for 60% surface coverage. And of course, the shade they provide also helps keep the algae at bay.

If you need more in the way of plant protection from your koi, you can actually make any size floating plant net you want using poly irrigation pipe and either fiberglas or plastic screen. I started with only goldfish but in the last few years have added koi. Haven't had much damage but I've headed a lot off with the floating baskets. Since I over winter and even try to grow water lettuce, I have more than the koi can handle so it doesn't get wiped out when I don't use the baskets. Both water lettuce and water hyacinth propgate quickly, but you need to give it a chance. Espeially the water hyacinth. You could protect a 'net' ful and as they over grow the net, toss the overage into the pond and see if your koi leave them alone.

But that's why a bog works well too; the plants help suck up the nutrients without the fish bothering them. Some folks here have used planters as bogs and placed them on the pond sides, letting the overflow go back into the pond. There's a few ways to retrofit a bog.
 
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Great, thanks, I'll look at adding planters as bogs. I'm trying to visualize the irrigation pipe and plastic screen - is this a habitat for the hyacinth, etc? To add some lotus (Nelumbo nucifera) I would need some sort of submerged version.....
 
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I've seen a neighbourhood cat eat some of the string algae at the edge of my pond.... :unsure:
 
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brokensword

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Great, thanks, I'll look at adding planters as bogs. I'm trying to visualize the irrigation pipe and plastic screen - is this a habitat for the hyacinth, etc? To add some lotus (Nelumbo nucifera) I would need some sort of submerged version.....
If you search 'bog' here, you'll find lots of threads. Basically you'll pump your water into the planter at the bottom. It rises up through your gravel and pours back into the pond. For a lotus, you're going to need a large tub--barrel size as lotus get huge. You may also get more resistance from its roots to easily take care of that kind of planted bog. The idea is you get aggressive (typically low growing) plants as they'll take up more nutrients faster. You then thin this plant herd as they take over your bog and they replicate all over again. With a lotus, you'll not easily do this so like @addy1 , you'll just let the water flow through this type of tub and then into a bog proper. There's issues re how deep the pipe, how deep the tuber, substrate etc so I'd not use a lotus as my main plant in my bog. I DO have a lotus in my mini bog but it's kept apart and the other plants do the job. The lotus is more for esthetics!
 
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Be careful not to damage your liner with that shrub rake. You said it was plastic, but be careful. Most people use a toilet brush to pull out string algae.

My koi will completely devour plants like fairy moss and the hanging roots of water hyacinths and water lettuce, so I float net them. As the plants multiply and fill the floating nets, I release them freely into the pond.
I use floating nets I bought on Amazon. You can make them if you like.
 

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With a lotus, you'll not easily do this so like @addy1 , you'll just let the water flow through this type of tub and then into a bog proper.
My lotus are in a tub just for them, 300 gallon stock tank. They get a feed of dirty water from the big pond. I have three ponds that are in that loop, one has lilies, one the lotus, one parrots feather and other stuff. They all act as plant filters. My small stream ponds also act as plant filters. The deck ponds and stream get dirty water from the big pond.

The big pond is the only place water goes from the pond into the bog, back into the big pond. I have no string algae, green water etc.

My hot tub pond, 300ish gallons, has a planter working as a bog filter. I feed water up through the bottom via one tube, it flows up and out back into the pond. Lots of plants in the planter, mainly water willow.
 
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So much good info here! And I'm so happy that we're at a point in the pond hobby where we generally understand that algae is a symptom, not a problem in and of itself. It's telling you something is happening in the pond that's creating excess nutrients. Sun used to be blamed for algae - while the sun may make it nice and green, it doesn't cause the algae to grow. And not only is algae not a problem, it's actually nature's solution - if you don't have that algae growing in the pond, then where will the excess nutrients go? A healthy pond will always have a good amount of algae coating all the surfaces.

The best way to control OVERGROWTH of algae is indeed more plants in the pond. All kinds of plants. Plants in pots are somewhat effective but the real magic happens when you let them grow directly in the pond. That's why floating plants are so helpful - the roots are in direct contact with the water.

Water changes won't help, so I wouldn't worry about that. (That's the old "solution by dilution" theory.) Especially 100 gallons weekly in a 3500 gallon pond - like a drop in the bucket. Mature pond water is the goal.

UV doesn't address string algae at all - and as mentioned will only add more nutrients to the water by killing off the single celled floating algae.

Post a few phots of your pond and we can help point out some areas where you could add plants! Or build that bog!
 
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The original purpose of the pond was for the koi and I did learn that they will eat almost any plants, except string algae (and cattails) Would it be crazy to introduce some snails that might eat that stuff?? That was the gist of my question. I'd be happy with a coating of green stuff all over the pond liner, but the string algae are hideous.
The pond is pictured already. As I did mention there are two pretty big cattails (Typha) near the waterfall now. The don't seem to do much to absorb the excess phosphorous, etc. I also have a pot full of horsetails (Equisetum) but it's too tall to capture water from the water fall. I will look at some sort of protective custody system for some water ferns and perhaps hyacinth. About water changing - there is absolutely no rainfall here from about May to October and of course, salts accumulate. Those of you in wet climates are getting some amount of free distilled water all summer, what maybe 50 inches worth? Thanks for the idea about putting the lotus in a big tub outside the pond.
 
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So much good info here! And I'm so happy that we're at a point in the pond hobby where we generally understand that algae is a symptom, not a problem in and of itself. It's telling you something is happening in the pond that's creating excess nutrients. Sun used to be blamed for algae - while the sun may make it nice and green, it doesn't cause the algae to grow. And not only is algae not a problem, it's actually nature's solution - if you don't have that algae growing in the pond, then where will the excess nutrients go? A healthy pond will always have a good amount of algae coating all the surfaces.

The best way to control OVERGROWTH of algae is indeed more plants in the pond. All kinds of plants. Plants in pots are somewhat effective but the real magic happens when you let them grow directly in the pond. That's why floating plants are so helpful - the roots are in direct contact with the water.

Water changes won't help, so I wouldn't worry about that. (That's the old "solution by dilution" theory.) Especially 100 gallons weekly in a 3500 gallon pond - like a drop in the bucket. Mature pond water is the goal.

UV doesn't address string algae at all - and as mentioned will only add more nutrients to the water by killing off the single celled floating algae.

Post a few phots of your pond and we can help point out some areas where you could add plants! Or build that bog!
Very well said!
So many good points brought up.
 
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The original purpose of the pond was for the koi and I did learn that they will eat almost any plants, except string algae (and cattails) Would it be crazy to introduce some snails that might eat that stuff?? That was the gist of my question. I'd be happy with a coating of green stuff all over the pond liner, but the string algae are hideous.
The pond is pictured already. As I did mention there are two pretty big cattails (Typha) near the waterfall now. The don't seem to do much to absorb the excess phosphorous, etc. I also have a pot full of horsetails (Equisetum) but it's too tall to capture water from the water fall. I will look at some sort of protective custody system for some water ferns and perhaps hyacinth. About water changing - there is absolutely no rainfall here from about May to October and of course, salts accumulate. Those of you in wet climates are getting some amount of free distilled water all summer, what maybe 50 inches worth? Thanks for the idea about putting the lotus in a big tub outside the pond.
We introduced some trapdoor snails a couple years back in with our koi and goldfish... the fish loved them!
Only a few snails survived i think and thats because they found refuge in areas that the fish couldnt get into...
Snails are good, nice to have, but dont expect them to help you with your algae.
Keep an eye on how much you feed and like others have said, go with the flow... you will have some algae and its OK, the fish love it.
 
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Would it be crazy to introduce some snails that might eat that stuff?? That was the gist of my question.
You can buy trap door snails. They good for your pond, but I don't think they will help much with the string algae.

It's best to not fight it, but prevent it by getting to the root of the problem. Most likely excess nutrients. More plants will compete with the string algae.
 
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I'm going to try floating plants for the first time this year.
What time of year is best to add them? I assume now is a bit too early?
Can they survive the winter?
 
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Some of those floating plants such as water hyacinth and water lettuce are tropical, so they won't survive cold weather.
When purchasing them look to see if they are tropical or hardy. Hardy indicates they will survive cold weather.
 
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It's making more sense. The cattails (which don't appear in my little pond picture) have finally started growing vigorously. They've been dormant all winter, though in this climate the tops remain green year round. There's a period, say February and March here, that's too cool for the the cattails and horsetails to put out any growth but quite warm enough for the wicked string algae to take off. Now that the bigger plants are growing again and absorbing more of the phosphorus, the string algae have subsided. I do like the toilet brush idea, I think a toilet brush with a 7 foot handle could be quite the conversation piece.

The trap door snails seem interesting, is there any chance they'd transmit disease to the koi?

I do need to get some 'floating nets' and water ferns.
Thanks everyone.
 

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